JP5235449B2 - Cutting tools - Google Patents

Description

  The present invention relates to a cutting tool in which a coating film is formed on a base material.

  Conventionally, there has been known a cutting tool in which a single or plural titanium carbide layer, titanium nitride layer, titanium carbonitride layer, aluminum oxide layer, and titanium nitride aluminum layer are formed on a base material such as cemented carbide, cermet, or ceramic. It has been.

  Such cutting tools are increasingly used for heavy interrupted cutting where a large impact is applied to the cutting edge as the efficiency of recent cutting increases, and the coating film is applied under such severe cutting conditions. In order to suppress chipping and peeling of the coating film due to a large impact, improvements in fracture resistance and wear resistance are required.

  As a technique for improving the fracture resistance in the cutting tool, the grain size and the layer thickness of the aluminum oxide layer are optimized, and the texture coefficient on the (012) plane is set to 1.3 or more. By this, a technique (see Patent Document 1) that can form a dense and highly fracture-resistant aluminum oxide layer, and an organization coefficient on the (012) plane of the aluminum oxide layer is 2.5 or more, A technique (see Patent Document 2) that can improve the fracture resistance of an aluminum oxide layer by facilitating the release of residual stress in the aluminum oxide layer is disclosed.

Further, as a technique for improving wear resistance in the cutting tool, an aluminum oxide layer located immediately above the intermediate layer is formed by laminating two or more unit layers showing different X-ray diffraction patterns. Thus, a technique (see Patent Document 3) that can improve the strength and toughness of the coating is disclosed.
Japanese Patent No. 6-316758 JP 2003-025114 A JP 10-204639 A

  In the cutting tool described above, a coating film having strength, toughness, and adhesion to the intermediate layer is required on the rake face, whereas a coating film having hardness is required on the flank face. However, it is difficult to form separate coatings on the rake face side and the flank face surface both on the technical side and on the cost side, so that the performance required on the rake face side and the flank face side is not achieved. There is a need for a combined coating.

  In the methods described in Patent Document 1 and Patent Document 2, tool damage on the rake face that is prone to sudden chipping or chipping can be suppressed, but on the flank face, conversely, by reducing the hardness of the aluminum oxide layer, There has been a problem that rubbing wear due to contact of the metal tends to progress.

  On the other hand, in the method described in Patent Document 3, the properties such as strength and toughness of the aluminum oxide layer are improved. However, since the adhesion force of the aluminum oxide layer to the intermediate layer is insufficient, a strong impact is applied to the cutting edge. In some cases, there is a problem that tool damage such as film peeling and chipping occurs.

  Therefore, in view of the above problems, the present invention is excellent in wear resistance on the flank, chipping resistance on the rake face, and adhesion of the aluminum oxide layer to the intermediate layer by optimizing the balance of the characteristics of the coating film. The object is to provide a long-life cutting tool.

  In response to the above-mentioned problems, the present inventor has optimized the crystal orientation of the base metal side and the surface layer side in the aluminum oxide layer of the cutting tool so that the wear resistance on the flank face, the fracture resistance on the rake face, and the intermediate layer It has been found that the aluminum oxide layer can exhibit excellent performance in adhesion.

Of the present invention, the invention according to claim 1 is a cutting tool in which a coating film formed by laminating a plurality of layers on a base material is formed, wherein the coating film is at least in order from the base material side. An aluminum oxide layer having an α-type crystal structure having an intermediate layer containing titanium and oxygen, a first surface in contact with the intermediate layer, and a second surface located on the surface side of the first surface; The peak intensity ratio I (104) / I (012) between the peak intensity I (104) on the (104) plane and the peak intensity I (012) on the (012) plane detected by X-ray diffraction analysis in the aluminum layer is The second surface side is larger than the first surface side , and among the peak intensities detected by X-ray diffraction analysis in the aluminum oxide layer, the peak intensity I (104) on the (104) plane is the maximum. This The features.

In the above invention, the peak intensity ratio I (104) / I (012) is preferably in the range of more than 1 to 15 or less .

  According to the present invention, 1) improved wear resistance on the flank of the cutting tool, 2) improved fracture resistance on the rake face of the cutting tool, and 3) improved adhesion of the aluminum oxide layer to the intermediate layer of the cutting tool. A plurality of effects can be combined.

  Therefore, according to the cutting tool of the present invention, it becomes possible to perform stable cutting over a long period of time on the work material.

  Hereinafter, an embodiment of a cutting tool according to the present invention (hereinafter simply referred to as a tool) will be described.

  FIG. 1 is a schematic perspective view of an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the tool of FIG.

  As shown in FIG. 1, a rake face 2 is formed on the main surface of the tool 1, and a flank face 3 is formed on the side face, and a cutting edge 4 is formed on the intersecting ridge line portion between the rake face 2 and the flank face 3. Has been.

  As shown in FIG. 2, the tool 1 includes a base material 5 and a coating film 6 formed on the surface of the base material 5. The coating film 6 includes, in order from the base material 5 side, a lower layer 7, a titanium carbonitride layer 8, an intermediate layer 9 containing at least titanium and oxygen, and an aluminum oxide layer having an α-type crystal structure (hereinafter simply referred to as an aluminum oxide layer). 10, formed from the surface layer 11. The lower layer 7 and the surface layer 11 are made of titanium nitride. The intermediate layer 9 is formed immediately below the surface of the aluminum oxide layer 10 on the base material 5 side (hereinafter referred to as the first surface 10a). The surface layer 11 is formed immediately above the second surface 10b located on the surface side of the aluminum oxide layer 10 relative to the first surface 10a. In another embodiment of the tool according to the present invention, instead of titanium nitride, zirconium nitride, titanium oxide, carbonitride or carbide carbonitride may be used as the surface layer, and the surface layer is not provided. May be.

  In this example, among the peak intensities detected by X-ray diffraction analysis in the aluminum oxide layer 10, the peak intensity I (104) on the (104) plane and the peak intensity I (012) on the (012) plane The ratio I (104) / I (012) is larger on the second surface 10b side than on the first surface 10a side.

  When the aluminum oxide layer 10 having a strong peak intensity I (012) on the (012) plane is formed, the bond strength between crystal grains of the aluminum oxide layer 10 is weakened, the toughness is improved, and the rake face 2 of the tool 1 is increased. The strength against impact increases. Therefore, the adhesion of the aluminum oxide layer 10 to the intermediate layer 9 is improved by increasing the peak intensity I (012) on the (012) plane on the first surface 10a side of the aluminum oxide layer 10, that is, on the base material 5 side. Thus, it is possible to suppress a sudden defect due to peeling and destruction of the coating film 6 due to an impact at the time of cutting and a decrease in tool life due to abnormal wear.

  On the other hand, when the aluminum oxide layer 10 having a strong peak intensity I (104) on the (104) plane is formed, the crystal of the aluminum oxide layer 10 can be formed into a columnar shape. Thereby, the linear progress of the crack is suppressed and the chipping resistance is improved, and the hardness is also improved, so that the wear resistance is also improved. Therefore, on the second surface 10b side of the aluminum oxide layer 10, that is, on the surface layer 11 side, by increasing the peak intensity I (104) on the (104) plane, rubbing wear on the flank 3 due to contact with the work material is prevented. It is possible to reduce the reduction of the tool life.

  That is, by adopting the above-described configuration, it is possible to improve the chipping resistance on the rake face 2 and the wear resistance on the flank face 3, and suppress damage such as chipping and peeling of the coating film 6 during cutting. be able to.

  Next, a method for measuring the peak intensity in the aluminum oxide layer 10 will be described. In addition, as a method of measuring peak intensity, it measures using the apparatus of the X-ray diffraction analysis using a general CuK alpha ray. In determining the peak intensity of each crystal plane in the aluminum oxide layer 10, the JCPDS card No. The value of 2θ where the peak intensity of each crystal plane described in 10-173 appears was used.

  First, the peak intensity on the second surface 10b side is measured. Specifically, the X-ray diffraction analysis is performed on the coating film 6 in a state where the surface layer 11 is polished or the surface layer 11 is not polished. Even when X-ray diffraction analysis is performed without polishing or the like on the surface layer 11, the peak intensity I (012) on the (012) plane of the aluminum oxide layer 10 and the peak on the (104) plane. It is sufficient if the intensity I (104) can be measured.

  Next, the peak intensity on the first surface 10a side is measured. Specifically, first, a part of the coating film 6 is polished. Polishing is performed by brush processing using diamond abrasive grains, processing by an elastic grindstone, or blast processing. In addition, it is preferable to perform grinding | polishing until the film thickness of the aluminum oxide layer 10 becomes about one quarter before grinding | polishing. Thereafter, the polished portion of the coating film 6 is subjected to X-ray diffraction analysis under the same conditions as when the second surface 10b side is measured, and peak intensities I (012) and (104) on the (012) plane are measured. The peak intensity I (104) at the surface is measured.

  With respect to the X-ray diffraction analysis result on the first surface 10a side and the X-ray diffraction analysis result on the second surface 10b side measured by the above method, the peak intensity I (104) on the (104) plane and the (012) plane, respectively. A peak intensity ratio I (104) / I (012), which is a ratio with the peak intensity I (012), is calculated. Thereby, the peak intensity ratio I (104) / I (012) can be compared between the base material 5 side and the surface layer 11 side.

  The peak intensity ratio I (104) / I (012) is 0.5 ≦ I (104) / I (012) ≦ 15 on both the base material 5 side and the surface layer 11 side. Thereby, sufficient wear resistance and chipping resistance for cutting can be obtained.

  That is, by setting the peak intensity ratio I (104) / I (012) to 0.5 or more, excessive increase of particles having a large particle size related to I (012) on the (012) plane is suppressed. In addition, it is possible to suppress tool damage such as chipping due to dropout of particles. On the other hand, by setting the peak intensity ratio I (104) / I (012) to 15 or less, it is possible to suppress an excessive increase in the particles involved in the peak intensity I (104) on the (104) plane, and the aluminum oxide layer It can suppress that the intensity | strength of 10 and a fracture resistance fall.

  In particular, the peak intensity ratio I (104) / I (012) on the surface layer 11 side is 3 to 10, and the peak intensity ratio I (104) / I (012) on the base material 5 side is 0.8 to 3. preferable. Thereby, performance required on the base material 5 side and the surface layer 11 side can be made more appropriate.

  Of the peak intensities detected by the X-ray diffraction analysis in the aluminum oxide layer 10, the peak intensity I (104) on the (104) plane is the maximum on the surface layer 11 side and the base material 5 side. Thereby, since higher hardness can be obtained on the surface layer 11 side, the wear resistance is further improved. Further, on the base material 5 side, columnar crystals are present, so that wear resistance, chipping resistance and chipping resistance are improved, and columnar crystals and granular crystals are mixed appropriately, so that excessively large particles are present. The increase can be suppressed and film peeling can be suppressed.

  Next, the tool manufacturing method according to the present invention will be described.

(Preparation of base material)
First, the base material of the tool is fired. Specifically, metal powder, carbon powder, etc. are appropriately added to and mixed with inorganic powder such as metal carbide, nitride, carbonitride, oxide, etc., press molding, casting molding, extrusion molding, cold static After forming into a predetermined tool shape by a known forming method such as hydraulic press forming, it is fired in a vacuum or in a non-oxidizing atmosphere.

(Lower layer deposition)
In the present embodiment, the coating layer 6 is formed on the base material 5 by chemical vapor deposition (CVD).

  First, in order to form a titanium nitride layer as the lower layer 7 on the surface of the produced base material 5, the reaction gas composition is 0.1 to 10% by volume of titanium tetrachloride gas and 1 to 60% by volume of nitrogen gas. Then, the mixed gas consisting of the remaining hydrogen gas is sequentially adjusted and introduced into the reaction chamber. And the inside of a chamber is set to 800-1100 degreeC and 5-85 kPa, and the titanium nitride layer 7 is formed into a film.

  Further, in order to form a titanium carbide layer instead of the titanium nitride layer as the lower layer 7, the reaction gas composition is 0.1 to 30% by volume of titanium tetrachloride gas, 0.1 to 20% by volume of methane gas, and the rest A mixed gas composed of hydrogen gas is sequentially adjusted and introduced into the reaction chamber. And the inside of a chamber is set to 800-1100 degreeC and 5-85 kPa, and a titanium carbide layer is formed into a film.

(Deposition of titanium carbonitride layer)
In order to form the titanium carbonitride layer 8 immediately above the lower layer 7, the reaction gas composition is 0.1% to 10% by volume of titanium tetrachloride gas, 0% to 60% by volume of nitrogen gas, and methane gas. 0 to 0.1% by volume, acetonitrile gas is 0.1 to 3% by volume, and the remainder is hydrogen gas, which is adjusted and introduced into the reaction chamber. And the inside of a chamber is set to 800-1100 degreeC and 5-85 kPa, and the titanium carbonitride layer 8 is formed into a film.

(Interlayer deposition)
Next, the intermediate layer 9 is formed immediately above the titanium carbonitride layer 8. As a pre-process for forming the aluminum oxide layer, the method for manufacturing a tool according to the present invention includes a process C for forming a layer containing titanium, aluminum and oxygen and containing at least one of carbon and nitrogen, and titanium and oxygen. Step D for forming a layer containing at least one of carbon and nitrogen and not containing aluminum, and flowing carbon dioxide gas to the layer containing titanium and oxygen and containing at least one of carbon and nitrogen It is preferable that the step E is sequentially provided. This is preferable because the aluminum oxide layer can be easily formed in the (012) orientation and the (104) orientation. Hereinafter, the steps C to E will be specifically described.

  First, in Step C, titanium tetrachloride gas is 0.5 to 10% by volume, aluminum chloride gas is 0.5 to 7% by volume, carbon monoxide gas is 0.1 to 5% by volume, and methane gas is 0 to 10% by volume. %, Nitrogen gas is 0 to 40% by volume, and the remainder is hydrogen gas, which is adjusted and introduced into the reaction chamber. Thereafter, the inside of the chamber is set to 950 to 1050 ° C. and 5 to 50 kPa, the film formation time is 2 to 20 minutes, and a layer containing titanium, aluminum and oxygen and containing at least one of carbon and nitrogen is formed.

  Next, in Step D, titanium tetrachloride gas is 0.5 to 10% by volume, carbon monoxide gas is 0.1 to 5% by volume, methane gas is 0 to 10% by volume, nitrogen gas is 0 to 40% by volume, A mixed gas consisting of the remaining hydrogen gas is prepared and introduced into the reaction chamber. Thereafter, the inside of the chamber is set to 950 to 1050 ° C. and 5 to 50 kPa, and the film formation time is 2 to 15 minutes, and a layer containing at least one of titanium, oxygen, carbon and nitrogen and not containing aluminum is formed To do.

  In step E, only carbon dioxide gas is flowed into the chamber at 100% by volume, the reaction time is 5 to 30 minutes, and the surfaces of the two layers formed in step C and step D are oxidized.

(Formation of aluminum oxide layer)
Next, an aluminum oxide layer 10 is formed immediately above the intermediate layer 9. The method of manufacturing a tool according to the present invention includes a step A for forming an aluminum oxide layer in an atmosphere of a first mixed gas containing aluminum chloride gas and carbon dioxide gas in a predetermined volume ratio, and the first mixed gas. In comparison, a step B of sequentially forming an aluminum oxide layer in an atmosphere of a second mixed gas in which the volume ratio of the aluminum chloride gas and the carbon dioxide gas is increased to 1.2 times or more is sequentially provided. The aluminum oxide layer on the base material 5 side formed in the step A has a strong (012) orientation, and the aluminum oxide layer on the surface side formed in the step B becomes an aluminum oxide layer on the base material 5 side. Compared to (104) orientation is stronger. For this reason, the peak intensity ratio I (104) / I (012) between the peak intensity I (104) on the (104) plane and the peak intensity I (012) on the (012) plane is obtained by the above steps A and B. A larger aluminum oxide layer can be formed on the surface side than on the base material 5 side. Hereafter, the said process A and the process B are demonstrated concretely.

  First, in step A, aluminum chloride gas is 1.7 to 10% by volume, hydrogen chloride gas is 0.5 to 3.5% by volume, carbon dioxide gas is 0.8 to 4.0% by volume, and hydrogen sulfide gas is A mixed gas consisting of 0 to 0.4% by volume and the remainder consisting of hydrogen gas is introduced into the reaction chamber. And it sets to 950-1050 degreeC and 5-30 kPa, and forms an aluminum oxide layer into a film.

  Next, in step B, aluminum chloride gas is 2.5 to 15% by volume, hydrogen chloride gas is 0.5 to 3.5% by volume, carbon dioxide gas is 1.2 to 6.0% by volume, hydrogen sulfide gas. Is introduced into the reaction chamber with a gas mixture of 0.03 to 2% by volume and the remainder consisting of hydrogen gas. Then, it sets to 950-1050 degreeC and 5-30 kPa, and forms an aluminum oxide layer into a film. Note that the mixed gas used in the process B includes hydrogen sulfide gas, and the volume ratio of the hydrogen sulfide gas included in the mixed gas used in the process B is hydrogen sulfide included in the mixed gas used in the process A. It is preferable that it is larger than the gas volume ratio. Thereby, the film-forming speed of the aluminum oxide layer in the process B can be increased as compared with the film-forming speed of the aluminum oxide layer in the process A.

  Moreover, the said process A and the process B may be one process which changes the ratio of mixed gas continuously with time. In this case, the aluminum oxide layer to be formed is formed by one inclined layer. As a result, the interface between the aluminum oxide layer formed in step A and the aluminum oxide layer formed in step B is eliminated, and adhesion within the aluminum oxide layer can be improved.

(Surface layer deposition)
Next, in order to form a titanium nitride layer as the surface layer 11 immediately above the aluminum oxide layer 10, the reaction gas composition is 0.1 to 10% by volume of titanium tetrachloride gas, 1 to 60% by volume of nitrogen gas, The remaining mixed gas consisting of hydrogen gas is sequentially adjusted and introduced into the reaction chamber. And the inside of a chamber is set to 800-1100 degreeC and 5-85 kPa, and a titanium nitride layer is formed into a film.

  These layers may be formed by other film forming methods such as physical vapor deposition (PVD).

  Then, the tool manufactured using the said manufacturing method is demonstrated.

(Example)
First, 6% by mass of metallic cobalt powder having an average particle size of 1.2 μm and 0.5% by mass of titanium carbide powder having an average particle size of 2.0 μm with respect to tungsten carbide powder having an average particle size of 1.5 μm. Tantalum powder is added and mixed at a ratio of 5% by mass, and formed into a tool shape (CNMA 12020412) by press molding. Then, the binder removal process was performed and it fired for 1 hour in the vacuum of 1500 degreeC and 0.01 Pa, and produced the base material which consists of a cemented carbide. Thereafter, the fabricated base material was subjected to brush processing, and R honing was applied to the portion to be the cutting edge.

  Next, a coating film was formed on the base material of the cemented carbide by a chemical vapor deposition (CVD) method. 1 to 5 and a tool No. as a comparative example. 6-8 were produced.

  The above tool No. 1 to 8, first, X-ray diffraction analysis using CuKα rays is performed in a state in which the coating film is not polished, and the rake face and the flat face of the flank face are each at three arbitrary locations on the (104) plane. Peak intensity I (104) and peak intensity I (012) in the (012) plane were measured. At that time, the crystal plane having the strongest peak intensity was also measured. Next, the aluminum oxide layer is polished to a thickness of about a quarter of the thickness of the aluminum oxide layer. Similarly, by X-ray diffraction analysis, the peak intensity I (104) in the (104) plane and the peak intensity I ((012) in the plane (012) 012) was measured. Further, the crystal plane where the peak intensity was the strongest was also measured.

  In addition, the tool No. In the fracture surface of 1-8, the interface of a base material and a coating film was observed 5000 times with the scanning electron microscope (SEM), and the thickness of the aluminum oxide layer and the thickness of the intermediate | middle layer were measured, respectively.

  Table 2 shows the peak intensity ratio I (104) / I (012), the thickness of the aluminum oxide layer, and the thickness of the intermediate layer obtained by the above measurement. In addition, Table 1 shows the film forming conditions of each layer described in Table 2. In addition, the “thin film” described in Table 2 refers to a film having a thickness of about 0.02 μm to 0.5 μm.

  Next, under the following conditions, the tool no. 1 to 5 and a tool No. as a comparative example. A continuous cutting test and an intermittent cutting test were performed using 6 to 8 to evaluate wear resistance and fracture resistance.

(Continuous cutting conditions)
Work material: Ductile cast iron 4-slot sleeve material (FCD700)
Tool shape: CNMA120204
Cutting speed: 250 m / min Feed speed: 0.4 mm / rev
Cutting depth: 2mm
Cutting time: 20 minutes Others: Use of water-soluble cutting fluid Evaluation item: Observe the honing part of the cutting edge with a scanning electron microscope and measure the amount of flank wear in the direction perpendicular to the rake face at the part that is actually worn.

(Intermittent cutting conditions)
Work material: Ductile cast iron 4-slot sleeve material (FCD700)
Tool shape: CNMA120204
Cutting speed: 250 m / min Feed speed: 0.3 to 0.5 mm / rev (feed amount fluctuation)
Cutting depth: 2mm
Other: Use of water-soluble cutting fluid Evaluation item: Number of impacts leading to breakage
Observe peeling state of coating film on cutting edge with scanning electron microscope at 1000 impacts

  According to the results in Table 2, a tool No. which is a comparative example in which the peak intensity ratio I (104) / I (012) is not configured to be larger on the surface layer side than on the base material side. In Nos. 6 to 8, tool damage such as film peeling occurred, and the abrasion resistance and fracture resistance were insufficient.

  On the other hand, the tool no. In Nos. 1 to 5, film peeling hardly occurred, and in particular, the tool No. 1 in which the thickness of the aluminum oxide layer was 5 to 7 μm. Regarding 1 to 3, more preferable results were obtained. Tool No. with the highest peak intensity I (104) in the (104) plane on the surface side of the aluminum oxide layer. 2 to 4, tool no. It was revealed that the flank wear was less than those of 1, 5 and 8, and the wear resistance was particularly excellent.

It is a schematic perspective view of one Example of the cutting tool which concerns on this invention. It is a schematic sectional drawing of the cutting tool of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cutting tool 2 ... Rake face 3 ... Flank 4 ... Cutting blade 5 ... Base material 6 ... Coating film 7 ... Lower layer 8 ... Titanium carbonitride layer 9 ... Intermediate layer 10 ... Aluminum oxide layer 10a ... First surface 10b ... Second surface 11 ... Surface layer

Claims (2)

In a cutting tool in which a coating film formed by laminating a plurality of layers on a base material is formed,
The coating film, in order from the base material side,
An intermediate layer comprising at least titanium and oxygen;
An α-type crystal structure aluminum oxide layer comprising a first surface in contact with the intermediate layer and a second surface located on the surface side of the first surface;
Have
The peak intensity ratio I (104) / I (012) between the peak intensity I (104) on the (104) plane and the peak intensity I (012) on the (012) plane detected by X-ray diffraction analysis in the aluminum oxide layer Is larger on the second surface side than on the first surface side, and the peak intensity I (104) on the (104) plane is the largest among the peak intensities detected by X-ray diffraction analysis on the aluminum oxide layer. The cutting tool characterized by being. 2. The cutting tool according to claim 1, wherein the peak intensity ratio I (104) / I (012) is in a range of more than 1 and 15 or less .